1. Field of the Invention
The present invention relates to an improvement of characteristics of a thin metallic layer type magnetic recording medium. More particularly, it relates to remarkable improvements of magnetic characteristics and electromagnetic conversion characteristics.
2. Description of the Prior Arts
High density magnetic recording technology has been developed depending upon improvements of recording reproducing systems, running systems, magnetic heads and recording media etc. Among them, the characteristics required for the magnetic recording medium are to increase a coercive force and to increase a residual magnetic flux density so as to reduce a thickness of the magnetic recording medium as far as possible.
In the conventional coating type magnetic recording medium coated with a magnetic powder and an organic binder, it is not possible to eliminate the organic binder in principal. It is almost impossible to increase the residual magnetic flux density to greater than 3,000 to 4,000 gauss. Thus, it is considered to provide a thin metallic layer type magnetic recording medium which does not contain an organic binder, as an important problem.
The thin metallic layer type magnetic recording media have been obtained by forming a thin layer of an iron group element (metallic element, alloy of the iron group element or alloy of an iron group element and a third element other than iron group elements) by a vacuum evaporation, sputtering, ion-plating, ion beam evaporation or electrochemical method, on a non-magnetic substrate. Among these processes, the vacuum evaporation as the most industrially effective process has been further studied to find magnetic recording media having excellent electromagnetic conversion characteristics and excellent magnetic characteristics having multimagnetic layers as described below. The magnetic recording media have been further studied to find a characteristic fine structure of the magnetic recording media.